The present invention relates to packaging, and more particularly to metal aerosol containers and methods for same.
Aerosol containers in the U.S. are rated by the Department of Transportation into three internal pressure ratings. Unrated containers are rated for up to 140 psi. Category 2P containers are rated for up to 160 psi. Category 2Q containers are rated for up to 180 psi. The DOT ratings are related to buckle performance. The burst requirement is 1.5 times the above pressure ratings.
A type of popular, conventional aerosol can is referred to as a three piece can, in which the parts are (i) a can “body” formed by rolling a flat sheet and welding the vertical seam, (ii) a “bottom” attached to the body by a seam, and (iii) an “end” seamed onto the top of the body. The end is dome-shaped. A flange for seaming to the can body is formed at the bottom of the aerosol end. A curl for receiving a valve is formed at the top of the aerosol end. Prior art aerosol cans include steel ends on steel bodies, aluminum ends on aluminum bodies, and aluminum ends on steel bodies.
Another conventional aerosol can includes an integral bottom and body formed in a process referred to as impact extrusion, such as sold by Exal. The impact extrusion process rams a slug of aluminum into the can body shape. Impact extrusion forms a relatively thick base. Shaped cans are also in the marketplace.
U.S. Pat. No. 7,140,223, entitled “Method Of Producing Aluminum Container From Coil Feedstock,” discloses an aluminum aerosol container formed by a drawing and ironing process in which a blank cut from an coil is first drawn into a cup and then ironed to increase the sidewall height and reduce the sidewall thickness.
Aerosol cans are rated for significantly higher internal pressure than that for beverage cans, which typically are rated for 85 psi or 90 psi internal pressure. Most beverage cans are formed in a drawing and ironing process that begins with an aluminum (or steel) sheet. After a first stage draws a flat blank into a cup and the second stage irons the sidewall. Modern beverage cans have a base thickness of approximately 0.0105 inches.
Conventional 12 ounce, drawn and ironed beverage are produced in vast quantities. Some aluminum bottles, such as the Alumitek™ bottle shown in FIG. 6, are formed from a drawing and ironing process. The Alumitek™ bottle has a conventional 211 body (that is, a nominal diameter of two and eleven sixteenths inches), a beveled heel, a standing ring that is approximately 75% of the body diameter, and dome (not shown in FIG. 6) that is inboard of the standing ring. The top of the Alumitek™ bottle has a neck that tapers to a threaded opening and a roll-on pilfer-proof cap.